Production of active carbon



1932. K. s. c. BONE PRODUCTION OF ACTIVE CARBON Filed Oct. 20, 1926 6 5. Cifmlvmegly Patented Jan. 5, 1932 lTED STATES PATENT OFFICE.-

KENNETH SAMUEL CULLOCH BONE, OF GARSTON, LIVERPOOL, ENGLAND, ASSIGNOR TO WILSON BROTHERS BOBBIN COMPANY, LIMITED, OI GARSTON, LIVERPOOL,

ENGLAND PRODUCTION OF ACTIVE CARBON Application filed October 20, 1926, Serial No. 142,971, and in Great Britain March 18, 19%.

This invention relates to the production of active carbon for use, for example, to decolorize sugar and other chemical substances,

or to absorb gases and organic solvents by a process of the type in which calcium acetate is used as the finely divided wood-impregnating agent, and acetone is produced by distillation.

The invention has for its main object to provide improved methods and means .thereraised and heat is thus conveyed to the charge.

Up to the stage when the charge attains a. temperature of about 250 C. About 90 per cent. of the total distillates are obtained. including some wood creosote oil, this distillation and recovery being achieved without the usual preliminary production of wood tar insoluble in the distillate.

When the charge attains a somewhat higher temperature, say about 360 0., complete J removal of the remaining volatile matters is produced still without the production of tar insoluble in the distillate.

The distillation of the wood being now completed the temperature of the charge is raised to about 1000 C. or higher (either in the same stillor after transference to a second still) the carbon produced is then withdrawn from the still and washed free from ash and from the calcium carbonate resulting from decomposition of the pyrolignite of calcium or calcium acetate. 7

Instead of operating the process discontinuously as in the example given above, I prefer to operate continuously and the accompanvabove the other and in series relationship.

The first still a com rises a casing within which is dis osed a pair of members 0, (1 each formed with an external helical groove of somewhat coarse itch the two helices being of similar hand. T e two members are mounted in bearings and are adapted to be rotated in the same direction with the respective helical projections intermeshing in.order' to convey the impregnated material as alayer from a hopper e disposed at one end of the still to the outlet. The outlet f communicates with the inlet of the casing of the second still I), which latter is also provided with a similar pair of rotating helically grooved internal conveyors The fuel burner j is arranged below the still I) and. a refractory casing is is provided to conduct the hot products of combustion around the still 6 and then around a lead bath m which is provided for the still a. This lead bath comprises a casing partiall surrounding the casing of the still a and a apted to contain molten lead. The products of combustion finally escape through a chimney n disposed adjacent the inlet hopper.

The still a is preferably of somewhat greater length than the still I) and serves for performance of the first step in the process.

In continuous operation the heating of the still or retort a is so adjusted that the exit temperature of the distillate vapors is in the region approaching 450 C. It will be seen that as the feed of the impregnated material (at e) takes place at about atmosnheric temperature it is gradually and uni- E.

' tained together with pyroligneous acid and creosote oils without the formation of tars insoluble in the distillate and hence without.

the normal subsequent tar distillation; the only tars produced being those soluble inthe distillate. The distillate passes out of the retort for recovery by way of the duct 0.

In some cases additional ducts may be provided between the point of introduction of the material and the duct 0 shown in Figure 1 so as to enable different constructions of distillate to be drawn ofi" at will.

The material after passage through the still a is introduced into. the still 6 by way of the pipe f through which latter it is conveyed at hi h temperature (exceeding 1000 (3.). It is ischarged at p, and any usual or convenient means being observed to avoid oxidation of the now activated carbon product.

The washing of the carbon to free it from the distillate vapors including creosote oils produced in the retort up to this temperature and subsequently continuing the rise in temperature of the now carbonized wood to at least 1000 C.

2. A process of wood distillation which consists in impregnating the wood in finely divided form with calcium acetate, feeding the impregnated wood continuously as a layer through a retort so that the temperature of the impre nated wood rises uniformly to about 450 drawing ofi for recovery all the distillate vapors'produced in the retort up to this temperature and subsequently in a further retort causing the rise in temperature of the now carbonized wood to at least 1000 C.

In testimony whereof I have signed my ash and from calcium carbonate after withdrawal from the still I) is effected by the treatment with acetic acid, pyroligneous acid or hydrochloric acid in order to convert the calcium carbonate into Water soluble calcium acetate or chloride which is removed by a water wash.

The carbon when freed of acetates, carbonates or oxides of calcium (decomposition products of the impregnating substance) is dried in any suitable manner.

The methyl alcohol and acetone, etc. derived from the distillation of the wood are also recovered and these may be separated and purified in any known or convenient manner, the pyroligneous acid conveniently being utilized for preparing pyrolignite of calcium or commercial calcium acetate.

It will be appreciated that the present invention includes the direct production of acetone, methyl ethyl ketone, higher ketones and acetone oils, together with acetic acid, methyl alcohol and creosote oils during a preliminary stage in the production of activated carbon and one of the by-products produced, i. e. acetic acid, is readily available after conversion into calcium acetate for the treatment of further stock of wood.

Having now described my invention what I claim as new and desire to secure by Letters Patent is 1. A process of wood distillation which consists in impregnating the wood in finely divided form with calcium acetate, feeding the impregnated wood continuously as a layer through a retort so that the temperature of the impregnated wood rises uniformly to about 450 (1., drawing off for recovery all 

